Thousands of Scottish shipbuilding jobs have been secured after a £4billion deal for two new aircraft carriers was signed.

The announcement yesterday will see more than half of the massive ships built at Govan and Rosyth shipyards.

Rosyth has been chosen to do final assembly and completion of the hull blocks of the aircraft carriers - to be built in Govan and other UK yards - and will also launch the 65,000-tonne vessels.

A spokesman for the MoD said the construction of the carriers would sustain more than 3,000 jobs on the Clyde, and create or sustain more than 1,600 jobs at Rosyth over the next eight years.

Nicola Sturgeon, Govan MSP and Deputy First Minister, was delighted the contract had finally been confirmed.

She said: "This is excellent news for Govan, for the Clyde shipyards and for Scotland's shipbuilding industry.

"I welcome the Ministry of Defence's eventual commitment to signing this contract, which will help BAE systems maintain their excellent workforce on the Clyde.

"It is unfortunate that the shipyards and the workforce have faced significant delay from the Ministry of Defence in signing the contract leading to some uncertainty at the yards, but this is a good day for shipbuilding on the Clyde and in Rosyth."

Contracts for the project were signed in a ceremony on board the Navy's flagship, HMS Ark Royal, in Portsmouth

The ships - which will measure 280 metres long and will be capable of carrying up to 40 planes - are due to enter into service in 2014 and 2016.

The MoD said HMS Queen Elizabeth and HMS Prince of Wales will be the largest and most powerful surface warships ever made in the UK.

Both will be built by a group of companies known as the Aircraft Carrier Alliance, with much of the work carried out by BVT Surface Fleet, a newly formed consortium of BAE Systems and VT Group.

Paul Lester, BVT group chief executive, said: "The formal signing of the manufacturing contract for CVF is a major boost for our new joint venture and will ensure that UK shipbuilding has a healthy workload for several years to come."

The MoD said building the carriers would also create or sustain 1,200 jobs in Portsmouth, more than 400 jobs in Barrow-in-Furness, 145 jobs in Frimley, in Surrey, and 250 jobs in Bristol and Crawley. Once complete the ships will carry a crew of around 1,500 and up to 40 aircraft.

Baroness Taylor, minister for defence equipment and support, said: "This is truly a national project, involving companies from the Clyde to the Solent. Construction work will create or sustain around 10,000 UK jobs ."